[IMPALA-3273] LEAD and LAG do not support a column for the default value

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Impala 2.2
• Component/s: Backend
• Labels: built-in-function
• Target Version: Product Backlog
• Assignee: Unassigned
• Reporter: David Magaha
• Created: 30/Mar/16 18:52
• Updated: 23/Oct/18 22:06

Description

The default values for the LEAD and LAG functions fails when using a column.

ex: SELECT LEAD( column_name, 1, column_name ) FROM some_table

This will only work if the default value is a constant.

Here is some of the the grammar from SQL:2016:

<lead or lag function> ::=
  <lead or lag> <left paren> <lead or lag extent>
      [ <comma> <offset> [ <comma> <default expression> ] ] <right paren>
      [ <null treatment> ]

<default expression> ::=
  <value expression>

<value expression> ::=
    <common value expression>
  | <boolean value expression>
  | <row value expression>